Processes for inhibiting scale deposition



Patented Mar. 11, 1952 PROCESSESFOR INHIBITING SCALE ,DEPO SITION Louis T. Morison, Alhambra, Califi, 'assignor'to Petrolite Corporation, Ltd., Wilmington, DeL, -a-corporation of'Delaware NoDrawing. Application March 14, 1949, Serial No. 81,401

I "22 Claims.

"This invention relates to a process for removing from surfaces, particularly from"'pipes and other processing equipment, deposits of inorganic solids arising from'thepassage of aqueous mediatherethrough, and for inhibiting and preventingtheaccumulationof such deposits at such'places. My process is particularly adapted 'for use -in equipment used in producing and handling crude oil, since the water produced tromthe earth'along with the oil often deposits "morganic-solidsas'a scale in the'well-tubing, or, more commonly, in traps, heaters, or other sur- "faceequipment, and in some instances even in pipelines. My process 'is likewise valuable in controlling deposits-or scales of such inorganic solids which may accumulate in steam-generating equipment if somewhat hard waters are used. *Utilityof myprocess is not limited tosuch characteristic applications; it may be used in *ot-herinstances'wherescales or depositsof inor- -ganic'so'lids originating from naturally-occurring constituents of aqueous media constitute a nui- "sance in industrial or other activities.

at theoutset from'accumulations of'mu'd solids in the form of mud sheaths, the removal of whichis the subject-matter of my co-pending "application, SerialNo. 719,925, filed January 2,

I947, nowPatent No. 2,470,830, dated May 24, I949. Mud sheaths are essentially filterccakes of water-insoluble solids of natural claysolids or of "barite, iron :oxide, bentonite, or other inorganic scli'dsused in preparing and conditioning,

drilling'mud'andoriginally present as an aqueous suspension. The inorganic solids with which the present invention is concerned may be thought :of as being originally:water-soluble inorganlcxsolids, which have been precipitated as hardevraterscaleflby the application of-heat,

'theJossof carbon dioxide or some otherconstituent, orinsomecases by thezchillingof the agueous .-mediuin as it passes through .theconduitror'apparatus-which exhibits the scaling,,,etc. Accumulations of such solids are recurring problems.

.The process which constitutes ,mytinvention consists in applyin to .Vincrganic solid deposits "ofth'e'kind described, a:'chemical;reagent of the kind describedbelow, to the end that such inorganic solids are removed from the surfaces to which they originally adhered. By such means,

the :capacityv of pipes, towlines, pipelines, traps, tanks, pumps, and other equipment supporting "such-deposits is :materially increased. The {exact'cnatures of the .action taking place when ,my 'reagents'aresusedis unknown tome. It does not appear .tozbeza :true, solution process, however, for a .number ofs-reasons.

.It will be apparent that if my reagents :are

applied ;to; a system which periodically accumulates such deposits of; inorganic solids-beforeappreciable deposition has occurred, and ,if such application of reagents is practised continuously or with sufficient frequency, the operation may be :considered a preventive process rather than .a corrective ,zone. If applied in somewhat insuffi- 'cient quantitytoaideposit already accumulated,

it may accomplish partial reduction of such deposit, ,rather than'complete. removal. My process is therefore both a preventive and a corrective one, and may be applied in either sense, .to achieve the same ,ultimate goal, ,viz., improvement of-the capacity .of conduits through which fluids are passed.

,Throughout this specification, therefore, I intend to say that my process is ,equally applicable to systemsin which a deposit of inorganic salts isalready in existence andtosystems which are potentially susceptibleto ,such deposition. -.When I have used the word inhibiting,,I-mean to. include therein the prevention, reduction, and removal ofgsuchldeposits of inorganic solids.

"Theireagentsawhich I employ in practising my process include ,a basic acylated aminoalcohol .in

which an1acyloxy:radical derived from a detergent formingacid having from 8 to 32 carbon atoms is joined;to.;a'basic nitrogen atom by a carbon atom chain, or a carbon atcm chain which is interrupted at least once by an ox en atom, said acylated jaminoalcohol being usually used diluted with a suitable diluent, such as water or a water-insoluble organic liquid capable of acting as an oil solvent.

In treating'systemsiniwhich oil is present, I prefer to mix the acylated .aminoalcohol with a water-insoluble organic liquid capable of acting asran oil solvent, and to employ such-;mixture in the form of a relatively stable aqueous dispersion. By relatively stable aqueous :dispersion, I mean one that is not resolved into its componentsspontaneously, on standing for protracted periods -'o'f time, e.-'g., for :more than one hour. However such preferred mixture may be employed undiluted or dispersed in oil. The acylated aminoalcohol may be mixed with water, especially if in salt form, to produce a relatively stable aqueous dispersion, and may be used as such or diluted further with water. In general, I believe the form of the reagent in which a water-insoluble organic liquid is incorporated gives superior results, at least where the system to be treated includes oil.

The basic acylated aminoalcohol employed in the present process includes an acylated derivative of a basic aminoalcohol of the formula:

said derivative being such that there is at least one occurrence of the radical RCO, which is the acyl radical of a monocarboxy detergent-forming acid having at least 8 and not more than 32 carbon atoms; the amino nitrogen atom is basic; R" is a member of the class consisting of alkanol radicals, aminoalkanol radicals, and polyaminoalkanol radicals, in which polyaminoalkanol radicals the amino nitrogen atoms are united by divalent radicals selected from the class consisting of alkylene radicals, alkyleneoxyalkylene radicals, hydroxyalkylene radicals, and hydroxyalkyleneoxyalkylene radicals, and all remaining amino nitrogen valences are satisfied by hydroxyalkyl radicals, including those in which the carbon atom chain is interrupted at least once by an oxygen atom; R is an alkylene radical having at least 2 and not more than 10 carbon atoms; and n is a small whole number varying from 1 to 10; RCO being a substituent for a hydroxyl hydrogen atom; and the molecular weight of said compound being at least 273 and not over 4,000, the preferred compound having a molecular weight not exceeding 1,000. The aminoalcohols may have more than one amino radical, or, for that matter, more than one basic amino radical. They are, to state it another way, esters of aminoalcohols which may contain ether linkages as well as more than one amino nitrogen atom. They are well-known compounds and are produced by conventional procedures.

The phrase basic amino nitrogen atom is used in its conventional sense. See, for example, Textbook of Organic Chemistry, Richter, second edition, page 253.

Reference to an amine and the subsequent amino compounds is intended to include the salts and the anhydro base. In instances where water is present, the term includes the hydrated base as well. Both the anhydro base and the hydrated base are obviously present when an aqueous system is being subjected to the reagent, or when the reagent is used as a water solution or dispersion. (In an aqueous solution of the amine, the anhydro base, RNH2, the hydrated base, RPNI-hOI-I, and the two ions are all pres ent. Richter, s. v., page 252.)

As previously stated, the acylated aminoalcohols with which the present process is concerned are old and well-known products, requiring no extensive discussion. For convenience and for purpose of brevity, reference is made to the following three U. S. patents to De Groote and Keiser, to wit: Nos. 2,324,488, 2,324,489, and 2,324,490, all dated July 20, 1943. Said patents are concerned with processes for breaking water-in-oil emulsions. The demulsifying agent employed is in each instance the resultant de- F rived by reaction between a certain fractional ester and an acylated aminoalcohol. The aminoalcohols described collectively in the aforementioned three patents are used as reactants for combining with a fractional acidic ester. Thus, said aminoalcohols must have present an alcoholiform hydroxyl as part of an acyl radical, or as part of a substituent for an amino hydrogen atom. In the instant case, such aminoalcohols are not employed as reactants, except as to salt formation reactions, and the hydroxyl group 15 not functional. Thus, one may employ, not only the aminoalcohols described in the three aforementioned United States patents, but also the obvious analogues in which there is no hydroxyl radical present. Subsequent reference will be made to this particular type and examples will be included.

The monocarboxy detergent-forming acids from which the acyl radical, RCO, of my acylated aminoalcohols is derived contain from 8 to 32 carbon atoms. They combine with alkali to produce soap or soap-like materials. They include fatty acids, rosin acids, petroleum acids, etc.; and all may be indicated by the formula R.COOH. The obvious equivalents of such acids, such as the halogenated or other derivatives retaining the carboxyl group, may be employed. The petroleum acids which may be employed include not only the naturally-occurring naphthenic acids, but also acids produced by oxidation of wax, parafiin, etc., as in U. S. Patent No. 2,242,837 to Shields, dated May 20, 1941.

The acylated aminoalcohol with which the present process is concerned is preferably derived from unsaturated fatty acids having 18 carbon atoms. Such unsaturated fatty acids include oleic acid, ricinoleic acid, linoleic acid, linolenic acid, etc. One may employ mixed'fatty acids, as, for example, the fatty acids obtained from hydrolysis of cottonseed oil, soyabean oil, etc. I prefer to employ C18 unsaturated acids containing a hydroxyl group. The whole class of high molal monocarboxy, detergent-forming acids is described in detail in aforementioned U. S. Patent 2,324,490.

As is well known, one need not use the high molal carboxy acid, such as a fatty acid, for introduction of the acyl group or acyloxy group. Any suitable functional equivalent such as the acyl halide, the anhydride, ester, amide, etc., may be employed.

The reagent employed in the present process includes an aminoalcohol ester, as described; and particular attention is directed to the fact that, although such esterified aminoalcohol need not contain a hydroxyl radical, my preferred form is the hydroxylated type. Other aminoalcohol esters of the kind herein contemplated are described in U. S. Patent No. 2,259,704, dated October 21, 1941, to Monson and Anderson.

In light of what has been said, it hardly appears necessary to include a list of reactants and reagents derivable therefrom. However, for convenience, the following amines are included. Suitable primary and secondary amines which may be employed to prepare suitable amino reactants, which latter are subsequently acylated to produce materials of the kind above described,

include the following: Diethanolamine, monoethanolamine, ethylethanolamine, methylethanolamine, propanolamine, dipropanolamine, propylpropanolamine, etc. cyclohexylolamine, dicyclohexylolamine, cyclohexylethanolamine, cyclohexyl propanolamine,

Other examples include forexampleglcy treating them with one or Elmore.

moles of an oxyalkylating agent, such :as ethylene oxide; propylene oxide, butylene oxide, i glyc- '=ide, e'tc. It is to be notedthatcomparable products are obtained by treating primary orisecondary amines other than arylamines with an olefineiox- *ide. Aminoalcdhols containing :azprimary 'orsecond'ary amino. group, i. e., having at least .one :or two amino hydrogen .atoms present,:may be Jemzploye'd under especially controlled conditions 1 to give'an ester,'rather lthanan amide. ionerprocedure istoipermit'amidification to take: place and then cause a rearrangement to the "esterfform. ilsee U. SUEatent No. 2,151,788, dated aMarch .223, 1939,1to1Mauersberger.

'A'MINOALC OHOL ESTER Example 1 Due *poun'd mole of "ricinoleic acid is reacted *with "one "pound mole of triethanolamine at approximately 180 to 240 C. forapproximately '1'0 to" 25 hours, until there is" substantially complete *esterification.

"Theric'inoleic acid may be repla'ce'd by-meth-yl "naphthenate, methyl abietateorethyl oleate.

AMINOALCOHOL ESTER Example 2 'l" 'One pound moleof triethanolamineis-reacted with-one pound mole .of ethyleneroxide and the zetherized amine so obtained is substituted for ttriethanolamine in Example 1.

Two to sixmoles ofethylene oxide may be em- -ployedinstea'dof one mole, to'prooluce other exramples of such etherized amines.

AMINOALCOHOL' ESTER Example '3 One pound 'mole of castor oil is'reacte'd with '73 pound moles of triethanolamine, as described in the aforementioned U. S. Patent No. 2,324,489, .to"De Groote and Keiser, under the heading-Inltermediate Hydroxylated :Amine, Example I11 v id'dditional examples are prepared in the manfner previously.v described, except that one: employs aminoalcohols obtained by .the oxyalkylation of ethylene diamine; diamylamine; morpholine; 1123-diamino-2 propanol; 2-amino-.:1--.butano1; I 2- samino-2-methyhlepropanol; --2- amino,-2+methyl-.

l'lj'3-tpropa'nediol; 2amino-2-ethyl-l,3 propane- 'diol; =tris-= (hydroxymethyl) aminomethane; 01' 'pizperidine. .Onemay use enough of the :olefine :ioxide, kifor;instance,Lethyleneioxide, toconvertaall 6 amino h-ydrogen atoms into 'ihydroxyethyl .Lradicals, or one may employ a greater amount 8018381130 introduce ether linkages iniad'dition. soybean oil, "blown soybean oil, tall oil, blown icastor oil, blown teaseed :oi1, etc., may :be used instead ;of castor oil in the a-bove example.

' In the above examples it is obvious that free "hydroxyl radicals -..may be present as part of a l'iydroxyalkylradical, or as part lof'theiacyl radical of a fatty acid-such as ricinoleic acid.

Some of the acylated aminoalcoholsusablewas ingredients in my reagentsaare freely dispersible in "water in the free state. Presumably, :such aqueous systems comprise the reagent'in theTform of a base, i. e., a substitutedsammoniumroom- :pound. mother-instances, thefree forms ofxthe reagents are substantially water-insoluble, "but t-he'salt forms .(e. 'g., the'acetates') area-very waterdispersible. I prefer to employ the acylated aminoalcohol in'Water-dispersibleform. In some instances, therefore, it .is desirable to "neutralize the acylated aminoalcohol to produce'a salt'which will be water-dispersible. :I have 'found for-example, that the acetate, hydroxyacetate, lactate, gluc'onate, propionate, 'caprate, 'phthalate, 'fumarate, m'aleate, .benzoate, .succinate, oxalate, tar- -trate, chloride, nitrate, cor sulfate, prepared by addition :of the suitable acid to the acylated i aminoalcohol, usually constitutes a .reagentwliich is somewhat more soluble or 'dispersibleiin water than the original acylated aminoalcohol. 'LItiis to be understood that references :to an'a'cylated aminoalcohol, .in these. specifications and :claims,

include the. reagent in the form of salts, as well ;as in the freeLform'andtthehydrated form.

..As"an example of :my preferred'itypeztof :acylated aminoalcohol reagent "which is effective as ran ingredient .Lin for as the composition used 1 my process, the following is submittedzil'prepareia Y mixture I of .diamino fand triamino: materials wliich correspond essentially to either one "of the :two following .type forms:

' NG2H4OC2H41 .HOLCiHi .C'zHrOH After determining the average molecular Weight of such mixtura'l combine the 'samewith the ricinoleyl radical by heating it with castor-oil in the proportionof 1 pound mole of castor oil 'for "'3 pound moles of-the' mixed amines, poundmole in the-latter'oasebeing calculated on theaverage -molecular"- Weight,as determined. Such mixture is heated. to approximately HO-"260 'C. for ap- "proximatelydto 25' hours,-until reaction is com- "plete, as indicatedtby 'the disappearance'of all of "the triricinolein-present in'the castor oil. Castor oil is used instead of some other sourceofithe "ricinoleyl radial, e. gx, Tremaine acid, in the ex- "ample, because of its ready-'commercial "av'ailability and lower price.

Depending upon the choice of acylated amino body and .its molecular weight, the solubility may "be expected to rangeifrom'ready water+solubility inithe free state: substantially to water-rin- :solubility. sAs stated above, the salts, "and :specifically 'the acetates, generally show :im-

proved Water-solubility .over vthe siniple acylated :amino bodies; rand I :have aobtainedpthe best :"results by "using :salt :fforms for :the :acylated aa-mino bodies which possess appreciable water-solubility.

For a number of reasons, it is usually desirable to mix the acylated aminoalcohol body with a-suitable diluent before use in my process. Water is sometimes the most desirable diluent, being cheap and available. In some instances, as above noted, especially where the scale-susceptible system includes oil, I prefer to use a waterinsoluble organic liquid which is capable of acting as an oil solvent, for diluent. Many materials lend themselves to this use. One of the commonest is the aromatic fraction of petroleum distillates which is quite generally found to disperse the acylated aminoalcohols. Edeleanu extract, which comprises aromatic and unsaturated compounds, is frequently found useful. In some cases, stove oil or similar petroleum distillate is usable. Oil solvents like carbon tetrachloride or carbon disulfide are usable, although their comparatively high cost militates against their use. Amylene dichloroide is sometimes a desirable material for the present purpose, as are tetrachloroethane, tetralin, trichloroethylene, benzol and its homologs, cyclohexane, etc. This component of my reagents should naturally be compatible with the other ingredient thereof; otherwise its selection is not limited. Cost and availability will influence the selection. I prefer to use aromatic petroleum solvent, as a widely available reagent of good properties and low cost, for the present use.

To prepare my reagents, when diluents are included with the acylated aminoalcohol ingredient, the components are simply mixed together inxsuitable proportions. The optimum proportion of each will vary, depending on its properties; but in general the resulting mixture should be homogeneous.

I also require that the finished reagent produce a relatively stable aqueous dispersion. In cases where the ingredients form thoroughly homogeneous mixtures which are not water-dispersible, the transformation of the acylated aminoalcohol component into its salt form will sometimes accomplish this purpose. In such cases, I have preferably used acetic acid to effect this neutralization.

The reagent may be employed in unidiluted form, except for the dilution employed in manufacture, to deliver it in readily usable form. In such cases, the reagent as compounded is simply introduced into the pipe or apparatus from whose surface a deposit or scale of inorganic solids is to be removed or deposition thereon inhibited. In such cases, there is undoubtedly produced an aqueous dispersion of the reagent if water is present in or passing through such apparatus. Such addition of undiluted reagent into a stream containing aqueous components may be considered equivalent to introducing a previously prepared aqueous dispersion of my reagent.

In most cases, an aqueous dispersion is obtained almost spontaneously on mixing with water my reagent prepared from the acylated aminoalcohol component and preferred nonaqueous diluent. I prefer to employ such embodiments of my reagent in aqueous dispersion, because, when 'so employed, the components of the reagent are prevented from separating from each other by the influence of oily materials present in the pipe or apparatus to be treated.

The present reagents have certain desirable properties. For example, they have been found to be quite stable in the presence of fairly saline water and in the presence of fairly hard water, over a period ranging from at least several hours to at least several days. My reagents do not form precipitates with quite hard waters and are not salted-out of appreciably saline waters. Since oil field waters are commonly saline and hard, stability toward such constituents is obviously desirable in a reagent to be used in the presence of such waters.

When a water-insoluble organic liquid is employed as diluent in preparing my reagents, I prefer to employ a considerable excess of acylated aminoalcohol over what would be exactly required to effect dispersion of the water-insoluble organic liquid in water. Such excess further prevents any separation of the phases, enhancing the stability of the dispersion so that it will remain stable for at least several hours. The excess of acylated aminoalcohol also acts to lower the surface tension of the whole reagent, be-

.cause of which the reagent exhibits a marked penetrating effect. In this way, it is carried into the crevices and irregularities of the deposit. weakening the bond between the deposit of inorganic solids and the supporting wall.

Where my reagents incorporate a water-inform in which it contained 4 parts of acylated aminoalcohol to 1 part of oil solvent. Ihave likewise prepared it in a form in which it contained 4 parts of oil solvent to 1 part of acylated aminoalcohol. Both forms were relatively stable, and did not separate appreciably into their components, on standing for protracted periods of time. I have likewise prepared my reagent in a form in which it contained 9. parts of acylated aminoalcohol and 1 part of oil solvent; and in a form in which it contained 1 part of acylated aminoalcohol and 9 parts of oil solvent. I have thereby determined that use of the acylated aminoalcohol and the oil solvent within the range of proportions, 9:1 and 1:9, is practicable, in producing my reagent. Therefore, I do not Wish to be limited to the exact proportions of ingredients recited in the following example, or to those specific ingredients recited, the example given being merely illustrative.

As a preferred example of reagent, I employ a 20% dispersion of the preferred acylated aminoalcohol mentioned above, in aromatic petroleum solvent, including 2% of concentrated acetic acid in the finished reagent. I prefer to employ this reagent in the form of a dilute aqueous dispersion, of about 5% concentration. Sometimes aqueous dispersions containing as little as 1% of the reagent are fully effective. Sometimes it is desirable to introduce the reagent in the form of a more concentrated aqueous dispersion, as when additional water is expected to be encountered in the system being treated. This preferred reagent may of course be introduced in undiluted form, if desired. It has been successfully so used.

From the foregoing, it will be understood that my invention, broadly stated, consists in subjecting a deposit of inorganic solids of the kind described above to the action of a reagent of the kind described. Merely introducing my reagent continuously into a scaled-up system usually results in the more or less complete removal of the scale within a reasonable time. Agitating the reagent in the system sometimes facilitates appenderemovahof" the scale:- deposit, as does allowing the. reagent toxstand: in: the system and soak it-fortany'desiredtime.

The theory; of the mode: of operationof my process is uncertain; butthe effects of applying the process are striking Capacity of pipesand apparatus is usually. promptly and markedly increased. Line pressures which haveincreased with: deposition of. the inorganic. solids fall; to normal within" a short time; and sometimessizeable: chunks of: the dislodged'de'posit are observed in thestream fromtthe wells or lines,,on screens inserted into such streams for; purposes or observation, or even,. at. times, .bytheir erosive. eifects on valves or. other equipment downstream. the deposit.

My reagents may be applied in many Ways, depending on the location andrcharacter-of'the depositofinorganicsolids it isproposed to remove orwh'ose deposition is to. be inhibited. In;the case of pipes, it: is usually; preferred to introduce, byfmeans ofa small proportioning pump, a continuous small stream of reagent; either undiluted or dilutedas. desired, upstream the deposit, until thelat-ter is dislodged and removed. In some apparatus, it-is. most practicableto-fill the whole withan aqueous. solution or dispersion of. the reagents and allow a' considerable soaking period to elapse before again pumping through the vessel. As stated above,.I prefer tolintroducemy reagents inaqueous dispersion,- and continuously, in small proportions, to -inhibitor to. remove inorganic: solid deposits of thekind here under. consideration. Theessential step-of my-process is that my reagent is brought into contactwith the deposit and the latter isthereby causedv to become dislodged from'its supporting surface.

The following specific examples will illustrate typical applications of my process.

An oil well wasproducing oil and water. The surface flow system from the well regularly accumulated a hard scale which included an appreciable proportion of carbonates precipitated from the oil well water. The scale was a compact, adherent'd'eposit, reaching thicknesses 'of or greater, in-the-header manifolds; trapvalves, rundownlines,- etc. Trapvalves at thehigh-- and low-pressure traps were favorable observation points; in that they scaled-up soonestaftercleaning; Generalpractice-atthis' location w'as'to produce thewell as long as possible, shut" down, and then remove the scale manually from all accessible-locations in the system; The operation-was required toberepeated at intervals of" about three weeks." 7

Myprefer-red' reagent was introduced' continuously; undiluted, intothe'system upstream the high-pressure trap; at the rate of 1'-- gallon to 1, 400" barrels" of water produced by the well.

Inspection of accessible points, which normally scaled-up within three weeks, was made-regularly fro'm' tlie beginning of such application of reagent After a month; 1 inspection showed a slightdeposit" of solids on the trap valves; very soft' 'and readily removable; Three months later, the injection of reagent was still continuing, the well had never-been? shutdown for scale removal, and there was no evidence of appreciable scale accumulation in the system.

' Furthento illustrate. theability of my reagents and: my process to eliminate is'cale deposits. com.- posed of: such inorganic-i solids; asecondexample wilrbecited. Itaillustrat'es,thesremovalzapproach, ratherthan.theinhibition"or-prevention approach anthe -previous "example;

An: oil; well production systemhad accumulated scale to; the; point where it: could handle only about 8,700 barrels of fluid daily against arated capacity of 12,000 barrelsdaily. Any attempt to increasethe flow-through the traps caused them to pop their contents of crude oil. My preferred reagent was injected at the well head, just downstream the fiow bean, after preliminary inspection of the degree of scale deposition had been made. such inspection had shown that flow valves. upstream the master trap, the manifold, and also thetrap discharge valve wereheavily sealed. The rateof reagentfeed- Was 1 quartto 1,500. barrelsofwell-water. Within 5 days after introduction of my reagenthad begun, sustained unrestricted-flow at 12,000 barrels daily was again effected.

Re-inspection' of accessible points 1 showed some of them to beentirely freefrom-scale deposits, points previously scaled hard. In other cases,,the scale hadnot been entirely removedin the short time of application of my reagent; but the remaining accumulationsv were. very soft in character.

This second; example illustrates the fact, that my process may be successfully applied as a scale-removing process and the fact that incomplete: removal-was found at several points in the system' after a. short period of treatment illustrates-the scale-reduction featureof my process.

In a third application of' my process, Lem.- ployed my preferred acylated aminoalcohol in theformof the acetate, prepared a a 15%solution in water. This material was introduced without further dilution into a pipe'carrying oil'and water, as in the preceding two. examples. Such introduction effectively inhibited the accumulationof-scale in such pipe.

Having. thus described: my invention, what I consider novel and: desire to secure by Letters Patent is:

1 A.proces s forpreventing, reducing andiremoving thedeposition of hard-water scale from the 1 surfaces ofequipmentof an aqueous scaleforming mediasystemby applyin to the aqueous scale-forming media system-a reagent comprising an acylated derivative of 1 a: basic aminoalcohol, the parent aminoalcohol havin the formula:

said derivative being such thatthere is at least one occurrenceof the radicalRCO, which is the acyl radical of-a monooarboxy detergent-forming acid having at leastitand not more than 32carbon atoms; the amino nitrogenatom isbasic; R" is a member. of the class consisting. of alkanol radicals,- aminoalkanol' radicals, and polyaminoalkanolradicals; in which polyamino alkanol radicals the am-inonitrogen atoms are united by divalent radicals selected from theclass, consisting of alkylene radicals, alkyleneoxyalkyleneradicals hydroxyalkylene radicals; and: hydroxyalkyleneoxyalkylene radicals, and all remaining amino nitrogen. valencesaresatisfied by hydroxyalkyl radicals, including those. inwhich the carbon' atomchain isinterruptedat least once by an oxygenatom R isan alkylene radical having at" least 2 and not, more than? 10: carbon atoms; and,v n. is asmall whole; number varying from. 1 to 10;,

2. A process, for preventing,;reducing and removing the deposition; ofhard-water scale: from 11 the surfaces of equipment of an aqueous scaleforming media system by applying to the aqueous scale-forming media system a reagent comprising an acylated derivative of a basic aminoalcohol, the parent aminoalcohol having the formula:

said derivative being such that there is at least one occurrence of the radical RCO, which is the acyl radical of a monocarboxy detergent-forming acid having at least 8 and not more than 32 carbon atoms; the amino-nitrogen atom i basic; R" is a member of the class consisting of alkanol radicals, aminoalkanol radicals, and polyaminoalkanol radicals, in which polyaminoalkanol radicals the amino nitrogen atoms are united by divalent radicals selected from the class consisting of alkylene radicals, alkylene oxyalkylene radicals, hydroxyalkylene radicals, and hydroxyalkyleneoxyalkylene radicals, and all remaining amino nitrogen valences are satisfied by hydroxyalkyl radicals, including those in which the carbon atom chain is interrupted at least once by an oxygen atom; R i an alkylene radical having at least 2 and not more than 4 carbon atoms; and n is a small hole number varying from 1 to 10.

3. The process of claim 2, wherein the acylated aminoalcohol contains more than one basic amino nitrogen atom.

4. The process of claim 2, wherein the acylated aminoalcohol contains at least 2 and not more than 4 basic amino nitrogen atoms and at least one free hydroxyl radical.

5. The process of claim 2, wherein the acylated aminoalcohol contains at least 2 and not more than 4 basic amino nitrogen atoms, a plurality of free hydroxyl radicals, and at least one ether radical.

6. The process of claim 2, wherein the acylated aminoalcohol contains at least 2 and not more than 4 basic amino nitrogen atoms, a plurality of free hydroxyl radicals, and at least one ether radical in a position other than part of the divalent linking radical which unites RCO with the nearest basic amino nitrogen atom; and wherein RC is a higher fatty acid acyl radical.

7. The process of claim 2, wherein the acylated aminoalcohol contains at least 2 and not more than 4 basic amino nitrogen atoms, a plurality of free hydroxyl radicals, and at least one ether radical in a position other than part of the divalent linking radical which unites RCO with the nearest basic amino nitrogen atom; and wherein RC0 is an unsaturated higher fatty acid acyl radical having 18 carbon atoms.

8. The process of claim 2, wherein the acylated aminoalcohol contains at least 2 and not more than'4 basic amino nitrogen atoms, a plurality of free hydroxyl radicals, and at least one ether radical in a position other than part of the divalent linking radical which unites RCO with the nearest basic amino nitrogen atom; wherein RCO, occurring only once, is an unsaturated higher fatty acid acyl radical having 18 carbon atoms; and wherein the value of n is unity.

9. The process of claim 2, wherein the acylated aminoalcohol contains at least 2 and not more than 4 basic amino nitrogen atoms, a plurality of free hydroxyl radicals, and at least one ether radical in a position other than part of the divalent linking radical which unites RCO with the nearest basic amino nitrogen atom; wherein RCO, occurring only once, is an unsaturated higher fatty acid acyl radical having 18 carbon atoms; wherein the value of n is unity and R is an alkylene radical having at least 2 and not more than 3 carbon atoms; and wherein the mo lecular weight is less than 1,000.

10. The process of claim 2, wherein the acylated aminoalcohol contains at least 2 and not more than 4 basic amino nitrogen atoms, a plurality of free hydroxyl radicals, and at least one ether radical in a position other than part of the divalent linking radical which unites RCO'with the nearest basic amino nitrogen atom; wherein RCO, occurring only once, is a ricinoleyl radical; wherein the value of n is unity and R is an alkylene radical having at least 2- and not more than 3 carbon atoms; and wherein the molecular weight is less than 1,000.

11. The process of claim 2, wherein the acylated aminoalcohol contains at least 2 and notmore than 4 basic amino nitrogen atoms, a plurality of free hydroxyl radicals, and at least one ether radical in a position other than part of the divalent linking radical which unites RCO'with the nearest basic amino nitrogen atom; wherein RCO, occurring only once, is an oleyl radical; wherein the value of n is unity and R is an alkylene radical having at least 2 and not more than 3 carbon atoms; and. wherein the molecular weight is less than 1,000.

12. A process for preventing, reducing and removing the deposition of hard-water scale from the surfaces of equipment of an aqueous scalesaid derivative being such that there is at least one occurrence of the radical RCO, which is the acyl radical of a monocarboxy detergent-forming acid having at least 8 and not more than 32 car bon atoms; the amino nitrogen atom is basic; R" is a member of the class consistingof alkanol radicals, aminoalkanol radicals, and polyaminoalkanol radicals, in which polyaminoalkanol radicals the amino nitrogen atoms are united by divalent radicals selected from the class consisting of alkylene radicals, alkyleneoxyalkylene radicals, hydroxyalkylene radicals, and hydroxyalkyleneoxyalkylene radicals, andall remaining amino nitrogen valences are satisfied by hydroxyalkyl radicals, including those in which the carbon atom chain is interrupted at least once by an oxygen atom; R is an alkylene radical having at least 2 and not more than 10 carbon atoms; and n is a small whole number varying from 1 to 10; RCO being a substituent for a hydroxyl hydrogen atom; and the molecular weight of said compound being at least 273 and not over 4,000; and (b) a water-insoluble oil solvent; the proportions of (a) and (b) lying between 1 to 9 and 13. A process for preventing, reducing and removing the deposition of hard-water scale from the surfaces of equipment of an aqueouslscaleforming media system by applying to the. aqueous scale-forming media'system a reagent comprising a mixture of (a) an acylated'derivative'of said derivative being such that there is at least one occurrence of the radical RCO, which is the acyl radical of a monocarboxy detergent-forming acid having at least 8 and not more than 32 carbon atoms; the amino-nitrogen atom is basic; R is a member of the class consisting of alkanol radicals, aminoalkanol radicals, and polyaminoalkanol radicals, in which polyaminoalkanol radicals the amino nitrogen atoms are united by divalent radicals selected from the class consisting of alkylene radicals, alkylene oxyalkylene radicals, hydroxyalkylene radicals, and hydroxyalkyleneoxyalkylene radicals, and all remaining amino nitrogen valences are satisfied by hydroxyalkyl radicals, including those in which the carbon atom chain is interrupted at least once by an oxygen atom; R is an alkylene radical having at least 2 and not more than 4 carbon atoms; and n is a small whole number varying from 1 to 10; RCO being a substituent for a hydroxyl hydrogen atom; and the molecular Weight of said compound being at least 273 and not over 4,000; and (b) a water-insoluble oil solvent; the proportions of (a) and (b) lying between 1 to 9 and 9 to l.

14. The process of claim 13, wherein the acylated aminoalcohol contains more than one basic amino nitrogen atom.

15. The process of claim 13, wherein the acylated aminoalcohol contains at least 2 and not more than 4 basic amino nitrogen atoms and at least one free hydroxyl radical.

16. The process of claim 13, wherein the acylated aminoalcohol contains at least 2 and not more than 4 basic amino nitrogen atoms, a plurality of free hydroxyl radicals, and at least one ether radical.

17. The process of claim 13, wherein the acylated aminoalcohol contains at least 2 and not more than 4 basic amino nitrogen atoms, a plurality of free hydroxyl radicals, and at least one ether radical in a position other than part of the divalent linking radical which unites RCO with the nearest basic amino nitrogen atom; and wherein RC is a higher fatty acid acyl radical.

18. The process of claim 13, wherein the acylated aminoalcohol contains at least 2 and not more than 4 basic amino nitrogen atoms, a plurality of free hydroxyl radicals, and at least one ether radical in a position other than part of the divalent linking radical which unites RCO with the nearest basic amino nitrogen atom; and wherein RC0 is an unsaturated higher fatty acid acyl radical having 18 carbon atoms.

19. The process of claim 13, wherein the acylated aminoalcohol contains at least 2 and not more than 4 basic amino nitrogen atoms, a plurality of free hydroxyl radicals, and at least one ether radical in a position other than part of the divalent linking radical which unites RC6 with the nearest basic amino nitrogen atom; wherein RCO, occurring only once, is an unsaturated higher fatty acid acyl radical having 18 carbon atoms; and wherein the value of n is unity.

20. The process of claim 13, wherein the acylated aminoalcohol contains at least 2 and not more than 4 basic amino nitrogen atoms, a plurality of free hydroxyl radicals, and at least one ether radical in a position other than part of the divalent linking radical which unites RCO with the nearest basic amino nitrogen atom; wherein RCO, occurring only once, is an unsaturated higher fatty acid acyl radical having 18 carbon atoms; wherein the value of n is unity and R is an alkylene radical having at least 2 and not more than 3 carbon atoms; and wherein the molecular weight is less than 1,000.

21. The process of claim 13, wherein the acylated aminoalcohol contains at least 2 and not more than 4 basic amino nitrogen atoms, a plurality of free hydroxyl radicals, and at least one ether radical in a position other than part of the divalent linking radical which unites RCO with the nearest basic amino nitrogen atom; wherein RCO, occurring only once, is a ricinoleyl radical; wherein the value of n is unity and R is an alkylene radical having at least 2 and not more than 3 carbon atoms; and wherein the molecular weight is less than 1,000.

22. A process for preventing, reducing, and removing the deposition of hard-water scale from the surfaces of equipment of an aqueous scaleforming media system by applying to the aqueous scale-forming media system a reagent comprising a basic acylated polyaminoalcohol; the parent polyaminoalcohol being a member of the class consisting of in which one hydroxyl hydrogen atom has been replaced by the ricinoleyl radical.

LOUIS T. MONSON.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 2,240,957 Munz May 6, 1941 2,400,543 Denman May 21, 1946 2,408,527 Monson Oct. 1, 1946 2,442,768 Gunderson June 8, 1948 2,470,830 Monson May 24, 1949 

1. A PROCESS FOR PREVENTING, REDUCING AND REMOVING THE DEPOSITION OF HARD-WATER SCALE FROM THE SURFACES OF EQUIPMENT OF AN AQUEOUS SCALEFORMING MEDIA SYSTEM BY APPLYING TO THE AQUEOUS SCALE-FORMING MEDIA SYSTEM A REAGENT COMPRISING AN ACYLATED DERIVATIVE OF A BASIC AMINOALCOHOL, THE PARENT AMINOALCOHOL HAVING THE FORMULA: 